1. Field of Invention
The present invention relates to a wash oscillator for a touchless car wash. More particularly, the invention relates to a wash oscillator that provides high impact wash or rinse action at essentially a right angle to the lateral surface of a vehicle being washed, particularly in a touchless car wash.
2. Related Art
The concept of touchless vehicle washing involves cleaning a surface without mechanical agitation such as can be provided by brushes or cloth. Detergents are applied to the surface to dissolve and loosen dirt and soil and pressurized water is used to remove both the detergent and the soil. Because of the electrical forces holding the partially dissolved and/or emulsified dirt on the vehicle surface, the pressurized water must impart a certain minimum impact to the surface to successfully remove the dirt.
Prior teachings regarding the touchless washing of vehicles are contained in U.S. Pat. Nos. 4,850,379 and 4,856,543, both of which are owned by the present inventor. A particular problem encountered in touchless vehicle washing is properly washing the lateral surfaces of the vehicle as it passes the wash station. The solution taught in the cited patents is a stationary vertical spray bar having a plurality of spray nozzles. Impact of the water from such a spray is directly related to several factors, including flow rate, pressure, distance from the surface and the angle of the impingement on the surface. While the vertical spray bar can provide a fixed impingement distance and angle, the vertical spray bar clearly requires a large number of such nozzles. For example, the spray bar necessary to cover the lateral surface of a van would typically require about ten nozzles, each having a 25 degree fan angle. Since the distance and pressure can be fixed, if a flow rate of 5 gpm were needed to obtain sufficient impact, such a device would typically require 50 gpm of water to effectively function. In the oscillator device taught in the present invention, the same result may be achieved with about two nozzles operating at the same flow rate, with a concomitant savings of 40 gpm of water. Alternatively, the flow rate through each nozzle may be increased, effectively increasing the impact. In an alternative known design, the same flow rate savings can be achieved by a horizontal spray bar that oscillates about the axis of the spray bar, but such a spray bar has a constantly changing angular impact with the surface as the bar oscillates, resulting in either unacceptably low impact at the extremes of the range or an overly high impact at the midrange. This changing angular impact is also undesirable. For example, if the angle of impact decreases from about 90 degrees to about 45 degrees, the impact force decreases by about 40%. Another known nozzle arrangement includes a pair of nozzles separated at the respective ends of a spray bar spinning about its midpoint. While this technique does possess certain advantages over the other techniques described above, the longitudinal separation of the nozzles requires that the spray begin to function as soon as the vehicle gets within the range of the nozzles at one-half of the bar length to the left of the midpoint and to continue until the vehicle gets one-half of the bar length to the right of the vehicle. During these extremes, at least one of the nozzles is spraying into the air and not impacting the surface.